Blender Cloth Simulation: Pinning, Sewing Springs and Pressure

What will you learn in this guide?

Blender’s cloth physics settings let you control not only how a mesh falls, but also which points are held in place and how it deforms. Pinning constrains specific points, while sewing springs pull vertices in separate areas toward each other. Internal springs and pressure can also be used for bulky, soft-body-like behavior beyond that of a cloth surface.

This guide first identifies the goal of each setting, then looks at shape, physical properties and pressure options in turn. The aim is not to prescribe fixed values for every scene, but to help you understand what each option changes so you can experiment with greater control.

Requirements

• Software: A Blender workspace with access to cloth physics settings and a mesh to use in the simulation.

• Version: The Blender manual pages referenced do not specify a particular version number. This guide therefore does not assume a version-specific interface or feature.

• Account and license: The sources do not provide information about account requirements or licensing costs.

• Optional preparation: You can create a vertex group for pinning and define its regions by painting weights. Dynamic Mesh, shape keys or deforming modifiers placed above the Cloth modifier can animate the cloth’s rest shape. The Rest Shape Key option is visible only when the mesh has shape keys.

The manual describes cloth options in the Shape and Physical Properties sections under Physics > Cloth. Rather than promising a specific result, the steps below explain what each setting does and what to watch out for.

Step-by-step: Set up cloth behavior

1. Define the motion you want

Start by describing how the mesh should behave in the scene. Will a piece of cloth move freely? Should an edge or area stay in place, or should two corners move toward each other? Are you working on a soft object that needs to retain volume? These questions help you choose between pinning and sewing springs in the Shape section, and internal springs and pressure in Physical Properties.

Focus on one behavior at a time. Instead of changing many settings at once, first observe the basic motion, then add constraints as needed.

2. Pin the areas that should stay in place

Pin Group uses a vertex group to specify the points where the cloth will be held. The weight assigned to each vertex affects how strongly that point is pinned. You can define the desired areas by painting weights.

Pinning can hold selected vertices in place or attach them to another object. This method is worth considering when you want to constrain a specific part of the cloth directly. After setting up the group, check how its weight distribution affects the simulation. Pinning too large an area can also restrict regions that should move freely.

3. Try sewing springs for vertices that need to come together

Sewing springs work differently from pinning: they create virtual connections that pull points in separate parts of the cloth toward each other. These connections are defined by edges added to the mesh that are not part of any face. The points you want to bring together should be connected by these edges. The manual gives the example of bringing the corners of a cape together.

Max Sewing Force sets the maximum force that sewing springs can apply. A value of zero means there is no force limit. According to the manual, it is generally best to avoid leaving this value at zero, as very high forces can cause instability—especially if the spring endpoints are far apart in the first frames of the simulation. Review the force limit while checking the initial distance between the connected points and how the cloth responds.

4. Review the cloth’s physical properties

The Physical Properties section includes settings such as cloth mass, air viscosity and the bending model. The Bending Model offers Linear and Angular options; the manual describes Linear as the older model.

Settings under Stiffness and Damping affect stretching, compression, shear and bending separately. Bending stiffness is described as a wrinkle coefficient that affects the formation of larger folds. Damping values determine how much these behaviors are damped. Changing one variable at a time makes it easier to identify which setting is responsible for the result.

5. Consider internal springs if you need volume

Springs on a cloth surface interact only across that surface. Internal Springs can help the mesh behave more like a soft body. This option is worth considering when you want volume rather than a thin surface.

Internal springs have limits such as the maximum length of springs that can be created and the angle by which connections can deviate from vertex normals. A maximum creation length of zero means no length restriction is applied. Check Surface Normals requires connected points to have opposite normal directions. Along with the Tension and Compression values, a vertex group can specify where internal springs are created or how strongly they act.

6. Check pressure options for closed objects

Pressure settings can be used to simulate soft-shell objects such as balloons or balls filled with fluid. Pressure is enabled by selecting the relevant panel option. The Pressure value defines the constant pressure applied to the mesh; negative values can be used to model inward pressure.

Pressure Scale affects resistance to changes in volume. Fluid Density specifies the density of the fluid inside the object; the manual gives a value of 1 for water. However, this setting does not simulate actual fluid motion. It can help produce more plausible resting shapes, but it does not generate fluid dynamics.

If the mesh has openings, pressure can escape through them and create drag or lift forces. The manual also describes using a vertex group to exclude the effect of such areas. When working with pressure, check the mesh’s integrity and the vertex group weights.

7. Choose a rest shape

Dynamic Mesh lets the cloth’s rest shape be recalculated at every frame. In work where the shape is animated using shape keys or a deforming modifier above the Cloth modifier, it can help unpinned cloth follow that change by compressing and stretching.

Rest Shape Key lets the simulation use a specific shape key as its initial rest state. This option is visible only when the mesh has shape keys, and it cannot be used at the same time as Dynamic Mesh. Consider this option when you need the cloth to start in a pre-draped shape.

Common mistakes

• Leaving sewing springs unlimited: A zero force limit means there is no limit. Corners that start far apart can cause high forces and instability.

• Ignoring openings when applying pressure to a mesh: Pressure can escape through holes; the manual recommends excluding the relevant areas with a vertex group.

• Confusing internal springs with surface springs: Unlike springs that act on the surface, internal springs can be used for soft-body-like behavior.

• Trying to use Dynamic Mesh and Rest Shape Key together: These options are mutually exclusive.

• Assuming Fluid Density simulates fluid: The density setting does not create actual fluid motion.

Impact on architectural and visualization workflows

Artists who want to control the shape of curtains, covers or soft decorative elements in interior visualizations can use pinning and sewing springs. Internal springs can be considered for soft objects that need a sense of volume, while pressure settings can be explored for closed objects that need a pressure effect. These tools help you set up more deliberately where the simulation is constrained.

The sources do not provide information about hardware requirements, performance figures, licensing terms or compatibility with other software. It is therefore important to run a small test in your Blender installation and confirm that the mesh is suitable for the method before moving on to a production scene.

Next steps

Start by choosing one method: pinning for a fixed area, sewing springs for corners that should move together, or internal springs and pressure for volumetric behavior. Observe the result, then adjust the relevant settings. If the motion is unexpected, check the vertex group weights, the initial distance between sewing spring endpoints, openings in the mesh and any shape options enabled at the same time—one at a time.

Sources and license

This guide is adapted into Turkish based on information in the official Blender manual pages for Shape and Physical Properties. Both sources are licensed under CC BY-SA 4.0.

• Blender Manual, “Shape”: https://docs.blender.org/manual/en/latest/physics/cloth/settings/shape.html

• Blender Manual, “Physical Properties”: https://docs.blender.org/manual/en/latest/physics/cloth/settings/physical_properties.html